JP7256617B2 - Intake system for internal combustion engine - Google Patents

Description

The present invention relates to an intake system for an internal combustion engine.

Patent Literature 1 discloses a technique of forming an air ejection port on a valve seat surface facing an intake valve in an intake port, and ejecting air from the air ejection port to a seating surface of the intake valve. According to this technology, it is possible to suppress deposits such as soot from accumulating between the seat surface and the valve seat surface of the intake valve.

JP-A-60-11606

A technique for more effectively suppressing deposits from accumulating on intake valves and intake ports is desired.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an intake system for an internal combustion engine that is highly effective in suppressing the accumulation of deposits on intake valves and intake ports.

In order to solve the above problems, an intake system for an internal combustion engine according to the present invention includes an intake passage, an intake valve for opening and closing an opening facing a combustion chamber downstream of the intake passage, and an intake valve for supplying compressed air to the intake valve. and a recirculation passage communicating between the downstream side of the intake passage and the upstream side of the intake passage whose pressure is lower than the pressure on the downstream side of the intake passage. and a head that protrudes in a direction intersecting the length of the shaft at the tip of the shaft and contacts the opening, and the air injection part is provided around the shaft and is attached to the head It has facing air jets.

In order to solve the above problems, an intake system for an internal combustion engine according to the present invention includes an intake passage, an intake valve for opening and closing an opening facing a combustion chamber downstream of the intake passage, and an intake valve for supplying compressed air to the intake valve. an air injection part that injects air; and a return path that communicates the downstream side of the intake flow path with the upstream side of the intake flow path whose pressure is lower than that of the downstream side of the intake flow path, the downstream side of the intake flow path. The recovery port that communicates the intake flow path and the return flow path on the side is located between the air injection port that injects air in the air injection portion and the opening of the intake flow path.

In order to solve the above problems, an intake system for an internal combustion engine according to the present invention includes an intake passage, an intake valve for opening and closing an opening facing a combustion chamber downstream of the intake passage, and an intake valve for supplying compressed air to the intake valve. An air injection part for injecting air, and a return path communicating the downstream side of the intake flow path and the upstream side of the intake flow path whose pressure is lower than that of the downstream side of the intake flow path, and are in an open state. A first valve that supplies compressed air to the air injection part and stops supplying the compressed air to the air injection part by being closed, and an intake valve that opens from the end of the intake stroke to the intake passage a first valve control unit that opens the first valve and causes the air injection unit to inject compressed air during at least a part of the period until the opening is completely closed. be .

In addition, the second valve that opens and closes the recirculation path and the second valve that is open during at least a part of the period from the end of the intake stroke until the intake valve completely closes the opening of the intake path. and a second valve control unit that moves the fluid on the downstream side of the intake channel to the upstream side of the intake channel through the return channel.

According to the present invention, it is possible to enhance the effect of suppressing the accumulation of deposits on the intake valve and the intake port.

1 is a schematic diagram showing the configuration of an internal combustion engine system; FIG. 4 is a partially enlarged view of an intake port; FIG. 1 is a perspective view of an intake valve; FIG. It is an explanatory view explaining the operation timing of an intake device. 4 is a flowchart for explaining the operation of a valve control section;

One aspect of an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in these embodiments are merely examples for facilitating understanding of the invention, and do not limit the invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are given the same reference numerals to omit redundant description, and elements that are not directly related to the present invention are omitted from the drawings. do.

FIG. 1 is a schematic diagram showing the configuration of an internal combustion engine system 1. As shown in FIG. In FIG. 1, the signal flow is indicated by dashed arrows. In the following, configurations and processes related to this embodiment will be described in detail, and descriptions of configurations and processes unrelated to this embodiment will be omitted.

The internal combustion engine system 1 includes an internal combustion engine 2 , an intake device 3 and a control device 4 . The internal combustion engine 2 is, for example, a reciprocating engine. Also, the internal combustion engine 2 is, for example, a four-stroke engine in which an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke are repeatedly performed. The internal combustion engine 2 includes a cylinder block 10 , a cylinder head 11 and pistons 12 .

A cylindrical cylinder 13 is formed in the cylinder block 10 . The piston 12 is slidably accommodated in the cylinder 13 . The crankcase 14 is integrally molded with the cylinder block 10 . A crank chamber 15 communicating with the cylinder 13 is formed in the crank case 14 . A crankshaft 16 is accommodated in the crank chamber 15 . Piston 12 is connected to a connecting rod 17 . A connecting rod 17 is connected to the crankshaft 16 .

A cylinder head 11 is joined to the cylinder block 10 so as to cover the opening of the cylinder 13 . A space surrounded by the cylinder 13 , the cylinder head 11 and the piston 12 becomes a combustion chamber 18 .

An intake port 20 and an exhaust port 21 opening to the combustion chamber 18 are formed in the cylinder head 11 . Although not shown, two intake ports 20 and two exhaust ports 21 are provided for one cylinder 13 . The cylinder head 11 is also provided with an intake valve 22 , an intake cam 23 , an exhaust valve 24 and an exhaust cam 25 . An intake valve 22 and an intake cam 23 are provided for each intake port 20 . An exhaust valve 24 and an exhaust cam 25 are provided for each exhaust port 21 .

The intake cam 23 reciprocates the intake valve 22 based on the rotation of the crankshaft 16 . The intake valve 22 opens and closes an opening 26 facing the combustion chamber 18 in the intake port 20 according to the intake cam 23 . The intake valve 22 will be detailed later.

The exhaust cam 25 reciprocates the exhaust valve 24 based on the rotation of the crankshaft 16 . The exhaust valve 24 opens and closes an opening 27 facing the combustion chamber 18 in the exhaust port 21 according to the exhaust cam 25 .

Also, the cylinder head 11 is provided with an injector 30 and a spark plug 31 . Injector 30 injects fuel into combustion chamber 18 . Note that the injector 30 may be provided in the intake port 20 . The spark plug 31 ignites a mixture of air and fuel. The piston 12 reciprocates within the cylinder 13 by combustion of the air-fuel mixture. Reciprocating motion of the piston 12 is converted into rotary motion of the crankshaft 16 through the connecting rod 17 .

The intake device 3 includes an intake passage 42 including an intake port 20, an intake valve 22, an air compression portion 51, a first valve 52, an air injection portion 53, a compressed air passage 54, a return passage 63 including a recovery port 60, a second 2 valves 62 are included.

An intake manifold 40 is connected to the intake port 20 . The intake manifold 40 is branched into a plurality of branch paths at a collective portion. Each branch of the intake manifold 40 is connected to each of the plurality of intake ports 20 . A collective portion of the intake manifold 40 is connected to an intake pipe 41 . The intake port 20, the intake manifold 40, and the intake pipe 41 form an intake passage 42 that introduces intake air (air) into the cylinder 13 (combustion chamber 18). Hereinafter, along the flow of intake air passing through the intake passage 42, the side farther from the internal combustion engine 2 is referred to as upstream, and the side closer to the internal combustion engine 2 is referred to as downstream.

The intake pipe 41 is provided with an air cleaner 43 and a throttle valve 44 in this order from the upstream side. The air cleaner 43 removes foreign matter mixed with the air sucked from the outside. The throttle valve 44 is opened and closed by an actuator 45 according to the accelerator opening. The amount of intake air sent to the combustion chamber 18 is adjusted according to opening and closing of the throttle valve 44 .

A first flow pipe 50 is connected between the air cleaner 43 and the throttle valve 44 in the intake pipe 41 . The first flow pipe 50 is connected to the air injection section 53 via the air compression section 51 and the first valve 52 . The first flow pipe 50 forms a compressed air flow path 54 branched from the intake flow path 42 . Hereinafter, in the compressed air flow path 54, the side farther from the air injection section 53 is called upstream, and the side closer to the air injection section 53 is called downstream.

The air compression section 51 is, for example, a high pressure pump. The air compression section 51 acquires and compresses the air in the air intake passage 42 through the first flow pipe 50 on the upstream side of the air compression section 51 . The air compression section 51 supplies the compressed air to the air injection section 53 through the first flow pipe 50 on the downstream side of the air compression section 51 . Henceforth, the air compressed by the air compression part 51 may be called compressed air.

The first valve 52 is provided between the air compression section 51 and the air injection section 53 . The first valve 52 is, for example, an electromagnetic valve, and opens and closes the compressed air flow path 54 . The first valve 52 supplies compressed air to the air injection section 53 by being in an open state, and stops supplying compressed air to the air injection section 53 by being in a closed state.

Air injection portion 53 is provided in intake port 20 . The air injection portion 53 injects compressed air to the intake valve 22 . Specifically, the air injection unit 53 injects the compressed air into the intake valve 22 when the first valve 52 is open, and stops injecting the compressed air when the first valve 52 is closed. The air injection portion 53 will be detailed later.

A recovery port 60 communicating with the intake port 20 is formed in the cylinder head 11 . A second flow pipe 61 is connected to the recovery port 60 . The second flow pipe 61 is connected between the air cleaner 43 and the throttle valve 44 via the second valve 62 . The recovery port 60 and the second flow pipe 61 form a return flow path 63 that communicates the downstream side and the upstream side of the intake flow path 42 . The recirculation path 63 recirculates the fluid on the downstream side of the intake flow path 42 to the upstream side of the intake flow path 42 . Hereinafter, in the return path 63, the side closer to the intake port 20 is called upstream, and the side farther from the intake port 20 is called downstream.

The second valve 62 is provided, for example, on the relatively downstream side (farther from the intake port 20 ) in the return passage 63 . The second valve 62 is, for example, an electromagnetic valve, and opens and closes the return path 63 .

Here, the upstream side of the throttle valve 44 in the air intake passage 42 is controlled to always have a negative pressure in order to facilitate intake of air from outside the internal combustion engine system 1 . Further, the upstream side of the throttle valve 44 in the intake passage 42 is controlled so that the pressure is lower than that in the intake port 20 .

Therefore, when the second valve 62 is opened, the fluid in the intake port 20 moves upstream of the throttle valve 44 in the intake passage 42 through the return passage 63 . On the other hand, when the second valve 62 is closed, no fluid movement through the return path 63 occurs.

An exhaust manifold 70 is connected to the exhaust port 21 . In the exhaust manifold 70, a plurality of branch paths are combined into one at a merging portion. Each branch passage of the exhaust manifold 70 is connected to a plurality of exhaust ports 21 respectively. A collective portion of the exhaust manifold 70 is connected to an exhaust pipe 71 . The exhaust port 21, the exhaust manifold 70, and the exhaust pipe 71 form an exhaust passage 72 through which the exhaust discharged from the cylinder 13 (combustion chamber 18) passes. A catalyst 73 is provided in the exhaust pipe 71 . The catalyst 73 is, for example, a three-way catalyst or the like, and removes hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) contained in the exhaust.

Further, the internal combustion engine system 1 is provided with an accelerator opening sensor 80 , a crank angle sensor 81 and a flow meter 82 . The accelerator opening sensor 80 detects the accelerator opening according to the depression amount of the accelerator pedal. A crank angle sensor 81 detects a crank angle, which is the rotation angle of the crankshaft 16 . The flow meter 82 is provided downstream of the throttle valve 44 in the intake pipe 41 and detects the amount of intake air supplied to the combustion chamber 18 .

The control device 4 is, for example, an ECU (Engine Control Unit). The control device 4 is composed of a semiconductor integrated circuit including a central processing unit (CPU), a ROM storing programs and the like, a RAM as a work area, and the like, and controls the internal combustion engine system 1 in an integrated manner. The control device 4 functions as a drive control section 90 and a valve control section 91 by executing programs.

The drive control unit 90 derives the current engine speed based on the crank angle detected by the crank angle sensor 81 . The drive control unit 90 derives the target torque and the target engine speed based on the current engine speed and the accelerator opening detected by the accelerator opening sensor. The drive control unit 90 determines a target air amount based on the target torque and the target engine speed, and determines a target throttle opening based on the target air amount. Then, the drive control unit 90 drives the actuator 45 so that the throttle valve 44 is opened and closed at the target throttle opening.

Further, the drive control unit 90 determines a target injection amount of fuel based on the target air amount, and determines a target injection timing and a target injection period based on the target injection amount. The drive control unit 90 drives the injector 30 at the target injection timing and the target injection period to inject the target injection amount of fuel. Further, the drive control unit 90 determines the target ignition timing based on the target engine speed and the crank angle, and drives and ignites the spark plug 31 at the target ignition timing.

The valve control unit 91 controls opening and closing of the first valve 52 and the second valve 62 according to the crank angle detected by the crank angle sensor 81 . The valve control unit 91 opens the first valve 52 and the second valve 62 during the period from the end of the intake stroke until the intake valve 22 completely closes the opening 26 of the intake port 20. The first valve 52 and the second valve 62 are closed. Further, the valve control unit 91 starts the operation of the air compression unit 51 when the internal combustion engine 2 is started, and stops the operation of the air compression unit 51 when the internal combustion engine 2 is stopped. The valve control unit 91 will be detailed later.

FIG. 2 is a partially enlarged view of the intake port 20. FIG. 3 is a perspective view of the intake valve 22. FIG. In FIGS. 2 and 3, the flow of compressed air is indicated by a solid arrow A1. Further, in FIG. 2, the flow of fluid containing unburned fuel such as an air-fuel mixture is indicated by a dashed-dotted arrow A2. Note that the illustration of the exhaust valve 24 is omitted in FIG.

The intake valve 22 is composed of a shaft portion 101 and a head portion 102 . The shaft portion 101 is formed in a bar shape. The umbrella portion 102 is formed in a substantially disc shape. The tip of the shaft portion 101 is continuous with the center of the umbrella portion 102 . In other words, the head portion 102 protrudes in a direction intersecting the length of the shaft portion 101 at the distal end of the shaft portion 101 . The intake valve 22 is arranged such that the shaft portion 101 is positioned on the intake port 20 side and the head portion 102 is positioned on the combustion chamber 18 side. The intake valve 22 is arranged such that the longitudinal direction of the shaft portion 101 coincides with the normal direction of the opening surface of the opening portion 26 .

A valve guide 103 is provided near the intake port 20 of the cylinder head 11 . The valve guide 103 is formed in a substantially cylindrical shape. The shaft portion 101 of the intake valve 22 is inserted through the valve guide 103 . The central axis of the valve guide 103 overlaps with the central axis of the shaft portion 101 . The valve guide 103 supports the intake valve 22 slidably in the longitudinal direction of the shaft portion 101 .

An intake cam 23 (not shown in FIGS. 2 and 3) is provided at the end of the shaft portion 101 opposite to the umbrella portion 102 . The intake valve 22 reciprocates in the longitudinal direction of the shaft portion 101 (in other words, in the direction normal to the opening surface of the opening 26) as the intake cam 23 rotates. The opening 26 of the intake port 20 is closed when the head portion 102 moves toward the intake port 20 and comes into contact therewith, and is opened when the head portion 102 moves toward and away from the combustion chamber 18 side.

A valve seat 104 is provided at the opening 26 of the intake port 20 . The valve seat 104 is, for example, ring-shaped. The valve seat 104 prevents a gap from forming between the opening 26 and the umbrella portion 102 when the opening 26 is closed by the intake valve 22 .

The air injection portion 53 is formed in a substantially cylindrical shape and provided around the valve guide 103 . That is, the air injection portion 53 is provided around the shaft portion 101 of the intake valve 22 . The air injection portion 53 is provided with an air injection port 105 through which compressed air is injected. The air injection port 105 is provided so as to face an umbrella back portion 106 which is a surface (rear surface) of the umbrella portion 102 on the shaft portion 101 side. The opening surface of the air injection port 105 has a ring shape surrounding the shaft portion 101 .

The air injection part 53 injects compressed air from the air injection port 105 . Compressed air jetted from the air jet port 105 moves along the shaft portion 101 toward the umbrella back portion 106 . Then, the compressed air that reaches the umbrella back portion 106 moves along the umbrella back portion 106 toward the peripheral edge of the umbrella portion 102 . That is, the air injection portion 53 injects compressed air so as to cover the shaft portion 101 and the umbrella back portion 106 .

The recovery port 60 is provided with a recovery port 107 that opens to the intake port 20 . The recovery port 107 allows the air intake passage 42 and the return passage 63 to communicate with each other. The recovery port 107 is provided near the valve seat 104 , that is, near the opening 26 of the intake port 20 . Specifically, recovery port 107 is provided between air injection port 105 and opening 26 of intake port 20 (more specifically, between air injection port 105 and valve seat 104). The opening area of the recovery port 107 is larger than the opening area of the air injection port 105, for example.

A plurality of collection ports 60 may be provided around the intake port 20 . In this case, the plurality of recovery ports 107 may be provided in a circumferential direction around the opening 26 of the intake port 20 . Also, in this case, the plurality of recovery ports 60 are gathered in the second flow pipe 61 .

FIG. 4 is an explanatory diagram for explaining the operation timing of the intake device 3. As shown in FIG. In FIG. 4, the crank angle at the start of the intake stroke is 0 degrees. Further, each stroke is switched each time the crank angle advances by 180 degrees.

The intake valve 22 begins to open shortly before the transition from the exhaust stroke to the intake stroke and keeps the opening 26 open during the intake stroke. Therefore, in the intake stroke, air is introduced into the cylinder 13 through the intake passage 42 and the opening 26 .

Further, in the intake stroke, fuel is injected into the cylinder 13 from the injector 30 . Therefore, in the intake stroke, a mixture of air and fuel is generated in the combustion chamber 18 . A mixture is a fluid containing unburned fuel.

The intake valve 22 does not completely close the opening 26 immediately after the intake stroke to the compression stroke. Then, the intake valve 22 completely closes the opening 26 after a predetermined crank angle has elapsed from the end of the intake stroke (the start of the compression stroke). In FIG. 4, the crank angle when the intake valve 22 completely closes the opening 26 is indicated by the crank angle CA1. Crank angle CA1 is set, for example, between 180 degrees and 270 degrees.

When moving from the intake stroke to the compression stroke, the piston 12 moves from the bottom dead center to the top dead center. Further, as described above, the opening 26 is open from immediately after the compression stroke until the time corresponding to the predetermined crank angle elapses. Therefore, from immediately after the compression stroke until the opening 26 is completely closed, part of the fluid containing unburned fuel in the combustion chamber 18 is It is pushed out to the intake port 20 through the opening 26 (see the dashed-dotted arrow A2 in FIG. 2).

In other words, the period from the end of the intake stroke until the intake valve 22 completely closes the opening 26 corresponds to the period during which the fluid containing unburned fuel is pushed out from the combustion chamber 18 to the intake port 20 . Hereinafter, the period from the end of the intake stroke until the intake valve 22 completely closes the opening 26 may be referred to as the blowback period. Fluid containing unburned fuel may also be referred to as unburned fluid. The unburned fluid is not limited to air-fuel mixture, and may be, for example, blow-by gas mixed with engine oil.

In addition, the temperature near the back portion 106 of the intake valve 22 and the opening portion 26 of the intake port 20 is lower than the temperature inside the combustion chamber 18 and is upstream of the intake passage 42 (for example, higher than the throttle valve). upstream).

Therefore, incomplete combustion of the unburned fluid pushed out from the combustion chamber 18 occurs near the back portion 106 of the intake valve 22 and near the opening 26 of the intake port 20 . That is, the vicinity of the back portion 106 of the intake valve 22 and the vicinity of the opening 26 of the intake port 20 are at temperatures within a predetermined temperature range where incomplete combustion is likely to occur. As a result, deposits such as soot accumulate on the back portion 106 of the intake valve 22 and the opening 26 of the intake port 20 . When deposits accumulate on the intake valves 22 and the intake ports 20, the intake resistance increases and the performance of the internal combustion engine 2 may deteriorate.

Therefore, the intake device 3 of the present embodiment injects compressed air from the air injection portion 53 so as to cover the shaft portion 101 and the umbrella back portion 106 (see solid arrow A1 in FIGS. 2 and 3).

Specifically, the valve control unit 91 closes the first valve 52 during the intake stroke. For example, the valve control unit 91 transmits a signal indicating valve closing to the first valve 52, and the first valve 52 is closed according to the signal indicating valve closing. The valve control unit 91 may close the first valve 52 by not transmitting a signal to the first valve 52 . Compressed air is not injected when the first valve 52 is closed.

The valve control unit 91 opens the first valve 52 when the intake stroke is switched to the compression stroke. For example, the valve control unit 91 transmits a signal indicating opening to the first valve 52, and the first valve 52 is opened according to the signal indicating opening. Compressed air is injected from the air injection port 105 when the first valve 52 is opened.

The valve control unit 91 keeps the first valve 52 open until the opening 26 is completely closed by the intake valve 22 (until the crank angle becomes equal to or greater than the crank angle CA1). Compressed air continues to be injected while the first valve 52 is maintained open.

The valve control unit 91 closes the first valve 52 when the opening 26 is completely closed by the intake valve 22 (when the crank angle becomes equal to or greater than the crank angle CA1). That is, when the opening 26 is completely closed by the intake valve 22, injection of compressed air is stopped. Then, the valve control unit 91 keeps the first valve 52 closed until the next intake stroke ends. In other words, compressed air is not injected during the period from when the opening 26 is completely closed by the intake valve 22 until the next intake stroke ends.

In this manner, the valve control unit 91 opens the first valve 52 and causes the air injection unit 53 to inject compressed air during the blowback period.

Since the intake device 3 of the present embodiment injects compressed air into the umbrella back portion 106 during the blowback period, the umbrella back portion 106 is protected by a layer of compressed air (in other words, an air curtain) and is not pushed out from the combustion chamber 18 . It is possible to prevent the unburned fluid that is discharged from contacting the umbrella back 106 . Therefore, the intake device 3 of the present embodiment can prevent deposits from accumulating on the back portion 106 of the intake valve 22 .

Note that in the case of the multi-cylinder internal combustion engine 2 , the air injection section 53 and the first valve 52 are provided for each intake valve 22 . Then, the valve control unit 91 performs opening/closing control of the first valve 52 for each cylinder 13 . Note that the air compression portion 51 may be shared by a plurality of first valves 52 (air injection portions 53).

In addition to injecting the compressed air, the intake device 3 of the present embodiment moves the unburned fluid to the upstream of the intake passage 42 through the recirculation passage 63 .

Specifically, the valve control unit 91 closes the second valve 62 during the intake stroke. For example, the valve control unit 91 transmits a signal indicating valve closing to the second valve 62, and the second valve 62 is closed according to the signal indicating valve closing. The valve control unit 91 may close the second valve 62 by not transmitting a signal to the second valve 62 . When the second valve 62 is closed, no movement of unburned fluid through the return path 63 occurs.

The valve control unit 91 opens the second valve 62 when the intake stroke is switched to the compression stroke. For example, the valve control unit 91 transmits a signal indicating opening to the second valve 62, and the second valve 62 is opened according to the signal indicating opening.

When the second valve 62 is opened, the pressure on the upstream side of the throttle valve is lower than the pressure in the intake port 20, so the unburned fluid pushed out from the combustion chamber 18 flows back through the recovery port 107. 63 (see dash-dotted arrow A2 in FIG. 2). The unburned fluid guided to the recirculation path 63 moves through the recirculation path 63 into the intake pipe 41 on the upstream side of the throttle valve 44 .

The valve control unit 91 keeps the second valve 62 open until the opening 26 is completely closed by the intake valve 22 (until the crank angle becomes equal to or greater than the crank angle CA1). While the second valve 62 is maintained open, unburned fluid pushed out of the combustion chamber 18 continues to move upstream of the throttle valve 44 through the return path 63 .

The valve control unit 91 closes the second valve 62 when the opening 26 is completely closed by the intake valve 22 (when the crank angle becomes equal to or greater than the crank angle CA1). That is, when the opening 26 is completely closed by the intake valve 22, movement of unburned fluid through the return passage 63 is stopped. Then, the valve control unit 91 keeps the second valve 62 closed until the next intake stroke ends. In other words, during the period from when the opening 26 is completely closed by the intake valve 22 to when the next intake stroke ends, no unburned fluid moves through the recirculation path 63 .

In this manner, the valve control unit 91 opens the second valve 62 during the blow-back period, so that the unburned fluid present in the vicinity of the opening 26 of the intake port 20 flows through the recirculation path 63 into the intake passage 42. Move upstream.

The intake device 3 of the present embodiment moves the unburned fluid to the upstream side of the intake passage 42 during the blowback period, so that the temperature of the opening 26 of the intake port 20 falls within the temperature range where incomplete combustion tends to occur. It is possible to prevent unburned fluid from staying in the vicinity. Therefore, the intake device 3 of the present embodiment can more effectively prevent deposits from accumulating on the umbrella back portion 106 of the intake valve 22 and the opening portion 26 of the intake port 20 .

The fluid moved to the upstream side of the intake passage 42 through the return passage 63 is not limited to the unburned fluid. For example, the compressed air injected from the air injection section 53 may also be moved to the upstream side of the intake flow path 42 through the return path 63 .

Also, the temperature on the upstream side of the intake passage 42 is lower than the temperature near the opening 26 of the intake port 20 as described above, and is lower than the temperature at which incomplete combustion occurs. Therefore, incomplete combustion of the unburned fluid moved to the upstream side of the intake passage 42 does not occur. As a result, no deposits due to displaced unburned fluid accumulate on the upstream side of the intake passage 42 .

Note that in the case of the multi-cylinder internal combustion engine 2 , the recovery port 60 and the second valve 62 are provided for each intake port 20 . Then, the valve control unit 91 performs opening/closing control of the second valve 62 for each cylinder 13 .

FIG. 5 is a flowchart for explaining the operation of the valve control section 91. As shown in FIG. The valve control unit 91 acquires the crank angle from the crank angle sensor 81 at predetermined time intervals (S100). Next, the valve control unit 91 determines whether or not the crank angle is smaller than 180 degrees indicating the end of the intake stroke (S110).

If the crank angle is less than 180 degrees (YES in S110), the valve control unit 91 closes the first valve 52 (S120) and closes the second valve 62 (S130). In addition, when the immediately preceding first valve 52 and the second valve 62 are closed, the valve control unit 91 maintains the closed state of the first valve 52 and the second valve 62 .

On the other hand, if the crank angle is not less than 180 degrees (is 180 degrees or more) (NO in S110), the valve control unit 91 determines that the crank angle indicates the point in time when the opening 26 is completely closed by the intake valve 22. It is determined whether or not it is greater than CA1 (S140).

If the crank angle is not greater than the crank angle CA1 (less than or equal to the crank angle CA1) (NO in S140), the valve control unit 91 opens the first valve 52 (S150) and opens the second valve 62. (S160). When the immediately preceding first valve 52 and second valve 62 are open, the valve control unit 91 keeps the first valve 52 and second valve 62 open.

On the other hand, if the crank angle is greater than the crank angle CA1 (YES in S140), the valve control unit 91 closes the first valve 52 (S120) and closes the second valve 62 (S130). In addition, when the immediately preceding first valve 52 and the second valve 62 are closed, the valve control unit 91 maintains the closed state of the first valve 52 and the second valve 62 .

As described above, the intake device 3 of the present embodiment not only injects compressed air into the intake valve 22 but also recirculates the unburned fluid from the downstream side of the intake passage 42 to the upstream side through the recirculation passage 63 .

Therefore, according to the intake device 3 of the present embodiment, it is possible to enhance the effect of suppressing the accumulation of deposits on the intake valve 22 and the intake port 20 .

Further, in the intake device 3 of the present embodiment, the air injection port 105 of the air injection portion 53 is provided around the shaft portion 101 so as to face the umbrella portion 102 . Therefore, the intake device 3 of the present embodiment can efficiently protect the umbrella back portion 106 with compressed air.

Further, in the intake device 3 of the present embodiment, the recovery port 107 on the upstream side of the return passage 63 is provided so as to be positioned between the air injection port 105 and the opening 26 of the intake passage 42 . Therefore, the intake device 3 of the present embodiment can efficiently move the unburned fluid pushed out from the combustion chamber 18 through the recirculation passage 63 .

Further, the valve control unit 91 of the intake device 3 of the present embodiment controls the first valve 52 during a period from the end of the intake stroke until the intake valve 22 completely closes the opening 26 of the intake passage 42 (blowing back period). is opened to cause the air injection part 53 to inject compressed air. Therefore, the air intake device 3 of the present embodiment can protect the umbrella back portion 106 more efficiently.

Further, the valve control unit 91 of the intake device 3 of the present embodiment closes the first valve 52 to stop the injection of the compressed air by the air injection unit 53 during the period other than the blowback period. As a result, extra compressed air is not injected in the intake stroke. Therefore, the intake device 3 of the present embodiment can suppress the influence on the control of the air-fuel ratio of the air-fuel mixture.

Further, the valve control unit 91 of the intake device 3 of the present embodiment controls the second valve 62 during a period from the end of the intake stroke until the intake valve 22 completely closes the opening 26 of the intake passage 42 (blowing back period). is opened to move uncombusted fluid through the return path 63 . Therefore, the intake device 3 of the present embodiment can move the unburned fluid pushed out from the combustion chamber 18 more efficiently.

Further, the valve control unit 91 of the intake device 3 of the present embodiment closes the second valve 62 to stop the movement of the unburned fluid through the recirculation passage 63 during periods other than the blowback period. As a result, in the intake stroke, the air on the downstream side of the intake passage 42 does not move to the upstream side of the intake passage 42 through the recirculation passage 63 . Therefore, the intake device 3 of the present embodiment can prevent the intake efficiency from decreasing during the intake stroke.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope of the claims, and it should be understood that these also belong to the technical scope of the present invention. be done.

For example, in the above embodiment, both the first valve 52 and the second valve 62 were open during the blowback period. However, the present invention is not limited to the mode in which both the first valve 52 and the second valve 62 are kept open during the entire blowback period. For example, the valve control section 91 may open the first valve 52 and the second valve 62 during a part of the blowback period. Also in this aspect, accumulation of deposits on the intake valve 22 and the intake port 20 can be suppressed.

Further, in the above embodiment, the opening/closing timing of the first valve 52 and the opening/closing timing of the second valve 62 match. However, the opening/closing timing of the first valve 52 and the opening/closing timing of the second valve 62 may be shifted. For example, the first valve 52 is opened and the second valve 62 is closed in the first half of the blowback period, and the second valve 62 is opened and the first valve 52 is closed in the second half of the blowback period. may be Also in this aspect, accumulation of deposits on the intake valve 22 and the intake port 20 can be suppressed. However, the accumulation of deposits on the intake valve 22 and the intake port 20 can be more effectively suppressed by matching the opening/closing timing of the first valve 52 and the opening/closing timing of the second valve.

In addition, in the above-described embodiment, the valve control section 91 corresponds to the first valve control section and the second valve control section of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be used for an intake device of an internal combustion engine.

2 Internal combustion engine 3 Intake device 13 Cylinder 18 Combustion chamber 20 Intake port 22 Intake valve 26 Opening 42 Intake flow path 52 First valve 53 Air injection section 62 Second valve 63 Recirculation path 91 Valve control section 101 Shaft section 102 Head section 105 Air injection port 107 Recovery port

Claims (4)

an intake channel;
an intake valve that opens and closes an opening facing the combustion chamber downstream of the intake passage;
an air injection unit that injects compressed air into the intake valve;
a return path communicating between a downstream side of the intake flow path and an upstream side of the intake flow path whose pressure is lower than that of the downstream side of the intake flow path;
with
The intake valve is
a rod-shaped shaft;
a canopy projecting in a direction intersecting the length of the shaft at the tip of the shaft and contacting the opening;
has
The air intake device for an internal combustion engine , wherein the air injection portion has an air injection port provided around the shaft portion and facing the head portion . an intake channel;
an intake valve that opens and closes an opening facing the combustion chamber downstream of the intake passage;
an air injection unit that injects compressed air into the intake valve;
a return passage that communicates a downstream side of the intake passage with an upstream side of the intake passage whose pressure is lower than that of the downstream side of the intake passage;
with
A recovery port that communicates with the intake flow path and the return flow path on the downstream side of the intake flow path is located between the air injection port that injects air in the air injection portion and the opening of the intake flow path. The intake system of the internal combustion engine located . an intake channel;
an intake valve that opens and closes an opening facing the combustion chamber downstream of the intake passage;
an air injection unit that injects compressed air into the intake valve;
a return passage that communicates a downstream side of the intake passage with an upstream side of the intake passage whose pressure is lower than that of the downstream side of the intake passage;
a first valve that is opened to supply compressed air to the air injection section and that is closed to stop the supply of compressed air to the air injection section;
During at least a part of the period from the end of the intake stroke until the intake valve completely closes the opening of the intake passage, the first valve is opened so that the air injection unit a first valve control unit for injecting compressed air;
An intake device for an internal combustion engine. a second valve that opens and closes the return path;
During at least a part of the period from the end of the intake stroke to the time when the intake valve completely closes the opening of the intake passage, the second valve is opened to allow the return passage to flow through the recirculation passage. a second valve control unit that moves the fluid downstream of the intake flow path to the upstream side of the intake flow path;
The intake system for an internal combustion engine according to any one of claims 1 to 3 , comprising:

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